Windows 7 Logon Background Changer is a free open source software that let you change the wallpaper of the Windows 7 logon screen (also known as "welcome screen", "login screen" or LogonUI)
dwnld
http://download.softpedia.com/dl/9a44d1 ... hanger.zip
yada
http://www.julien-manici.com/download/f ... hanger.zip